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    SubjectRe: [linux-pm] [PATCH v3] PM: add statistics debugfs file for suspend to ram
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    On Tue, 2011-08-09 at 13:49 +0900, MyungJoo Ham wrote:
    > On Tue, Aug 9, 2011 at 11:27 AM, Liu, ShuoX <shuox.liu@intel.com> wrote:
    > > From: ShuoX Liu <shuox.liu@intel.com>
    > >
    > > Record S3 failure time about each reason and the latest two failed
    > > devices' names in S3 progress.
    > > We can check it through 'suspend_stats' entry in debugfs.
    > >
    > > The motivation of the patch:
    > >
    > > We are enabling power features on Medfield. Comparing with PC/notebook,
    > > a mobile enters/exits suspend-2-ram (we call it s3 on Medfield) far
    > > more frequently. If it can't enter suspend-2-ram in time, the power
    > > might be used up soon.
    > >
    > > We often find sometimes, a device suspend fails. Then, system retries
    > > s3 over and over again. As display is off, testers and developers
    > > don't know what happens.
    > >
    > > Some testers and developers complain they don't know if system
    > > tries suspend-2-ram, and what device fails to suspend. They need
    > > such info for a quick check. The patch adds suspend_stats under
    > > debugfs for users to check suspend to RAM statistics quickly.
    > >
    > > If not using this patch, we have other methods to get info about
    > > what device fails. One is to turn on CONFIG_PM_DEBUG, but users
    > > would get too much info and testers need recompile the system.
    > >
    > > In addition, dynamic debug is another good tool to dump debug info.
    > > But it still doesn't match our utilization scenario closely.
    > > 1) user need write a user space parser to process the syslog output;
    > > 2) Our testing scenario is we leave the mobile for at least hours.
    > > Then, check its status. No serial console available during the
    > > testing. One is because console would be suspended, and the other
    > > is serial console connecting with spi or HSU devices would consume
    > > power. These devices are powered off at suspend-2-ram.
    > >
    > > Thank Greg and Rafael for their great comments.
    > >
    > > Change Log:
    > > V3: Change some programming styles.
    > > V2:
    > > 1) Change the sysfs entry to debugfs.
    > > 2) Add some explanation in document file.
    > >
    > > Contribution:
    > > yanmin_zhang@linux.intel.com
    > >
    > > Signed-off-by: ShuoX Liu <shuox.liu@intel.com>
    > > ---
    > > Documentation/power/basic-pm-debugging.txt | 19 +++++++++
    > > drivers/base/power/main.c | 35 ++++++++++++++--
    > > include/linux/suspend.h | 16 +++++++
    > > kernel/power/main.c | 59 ++++++++++++++++++++++++++++
    > > kernel/power/suspend.c | 15 ++++++-
    > > 5 files changed, 136 insertions(+), 8 deletions(-)
    > >
    >
    > This patch looks very helpful. Great! :)
    >
    > Anyway, how about including the error value induced by the device
    > along with the device name?
    > For example,
    >
    > failed_devs:
    > last_failed: alarm -5
    > adc -10
    >
    > or
    >
    > failed_devs:
    > last_failed: alarm
    > adc
    > last_errorno: -5
    > -10
    >

    > Or, even, we may consider including the failed step:
    > failed_devs:
    > last_failed: alarm
    > adc
    > last_errorno: -5
    > -10
    > last_step: suspend
    > suspend_noirq
    >
    It's a good idea! We would change it to output like above format.

    Thanks MyunJoo.




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